斜直井中钻柱螺旋屈曲的非线性有限元分析

建立了斜直井中有重钻柱螺旋屈曲非线性有限元分析方法，提出了对重力相关项的处理方法，在力学模型中考虑了重力、扭矩和井斜角对临界载荷的影响，并将计算结果与理论分析做了比较。分析结果表明，本文建立的有重钻柱螺旋屈曲非线性有限元分析方法是正确的，在相同条件下钻柱螺旋屈曲临界载荷随井斜角增大而增大，且呈非线性；临界载荷随扭矩增大而减小，且井斜角较大时减小幅度较大；钻柱重力线密度对临界载荷的影响大小与井斜角和屈曲模态有关。

Nonlinear Finite Element Analysis for Helical Buckling of Tubing in Deviated Wells

A method for nonlinear finite element analysis of the he lical buckling of tubing in deviated wells is presented for the first time, and i t is used to treat the item of the gravity. The effects of gravity, torsion and deviation angle of wells on the helical buckling critical load are considered wi th a mechanical model. Calculational results are compared with the analytica l values. It is shown by the comparisons that the finite element formulations ar e correct. Under the same conditions the helical buckling load increases nonline arly with the increase of the well deviation angle. Torsion can reduce the helic al buckling load, and the degree of reduction increases with the increase of dev iation angle. The effect of the tubing weight per unit length on the buckling lo ad varies with the deviation angles and buckling mode.